The present invention relates to a semiconductor device such as a twin transistor package on which two transistor chips are mounted.
In the market of mobile communication, higher-gain, lower-noise, smaller-size, and lower-cost devices are requested, and high-performance, compact semiconductor devices are accordingly required. To meet this demand, twin transistor packages in which the packaging area and the number of packaging steps are reduced have conventionally been merchandized.
FIG. 9 shows the arrangement of components in a conventional twin transistor package.
Each of transistor chips (transistor pellets) Q11 and Q12 has a collector electrode on its lower surface and a base electrode and emitter electrode on its upper surface. The base electrode of the transistor chip Q11 and the inner lead portion of a base lead 31 are connected to each other through a base bonding wire 41. The emitter electrode of the transistor chip Q11 and the inner lead portion of an emitter lead 33 are connected to each other through an emitter bonding wire 42.
The base electrode of the transistor chip Q12 and the inner lead portion of a base lead 35 are connected to each other through a base bonding wire 44. The emitter electrode of the transistor chip Q12 and the inner lead portion of an emitter lead 37 are connected to each other through an emitter bonding wire 45. The inner lead portions of collector leads 32 and 36 respectively serve also as die pads 34 and 38 for placing the transistor chips Q11 and Q12 thereon.
In the twin transistor package described above, the gain and transition frequency of the transistor chip Q11 decrease. This is because since the base lead 31 of the transistor chip Q11 and the collector lead 32 are adjacent to each other, isolation between them is poor, and the collector-base capacitance becomes, e.g., about 80 fF.
Also, since the inner lead portion of the emitter lead 33 has a small bondable area, the emitter bonding wire 42 can be provided only one, and the emitter inductance of the transistor chip Q11 accordingly increases. The gain and transition frequency of the transistor chip Q12 also decrease from the same reason.